Snap action, double throw switch



D. D. CAMPBELL ET AL 3,286,050

SNAP ACTION, DOUBLE THROW SWITCH Nov. 15, 1966 2 Sheets-Sheet 1 Filed Oct. 21, 1964 M m mu EO V: NBT E w N J NMw R 8 A o 4 CC "H 0 5 n A 4 Lr 3 VA 2 J 4 m M w j H U M16 b 8 Q 4 b 5 a 7. 6 5 HH L F Nov. 15, 1966 D. CAMPBELL ET AL 3,286,050

SNAP ACTION, DOUBLE THROW SWITCH Filed Oct. 21, 1964 2 Sheets-Sheet 2 l2 /2 i i INVENTORS DA V/D D. CAMPBELL JAMES C. LOUTON JR.

A TTORNE) United States Patent O 3,286,050 SNAP ACTION, DOUBLE THROW SWITCH David D. Campbell, Birmingham, and James C. Louton,

3n, Utica, Mich., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Oct. 21, 1964, Ser. No. 405,526 7 Claims. (Cl. 200-47) This invention relates to limit switches and more particularly to a type of electric switch responsive to movement of an object near an intended extreme of movement.

It is desirable in the use of limit switches that carry high amperage to have a very rapid switching action take place. Limit switches by their very nature require a very fast switching action to minimize the error allowed an object whose movement is being limited. The subject invention incorporates into a single switch, normally associated with high amperage electrical circuits, the desirable features of very quick switch contact movement and the feature of being adjustable after final mounting to accommodate a minor variance in the tolerance between the switch as mounted and an object whose movement is to be limited.

It is an object of the present invention to provide an improved electric switch adapted to very quickly switch high amperage circuits.

It is another object of the present invention to provide an improved electric switch used as a limit switch which is adapted to carry high amperage loads and which is automatically adjustable to a desired clearance between the switch as mounted and an object whose movement is to be limited.

It is still another object of the present invention to provide an improved electric switch which has a minimum number -of moving parts and is adapted to be operated repeatedly without any disruption of internal tolerances.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein preferred embodiments of the present invention are clearly shown.

In the drawings:

FIGURE 1 is a vie-w of the subject invention illustrated in an operative environment;

FIGURE 2 is an exploded perspective view of the subject invention;

FIGURE 3 is an elevational view of the switching contacts of the subject invention shown in two operative positions;

FIGURE 4 is a sectional view taken along line 4-4 of FIGURE 1;

FIGURE 5 is a sectional view taken along line 55 of FIGURE 4 FIGURE 6 is a sectional view similar to FIGURE wherein the switch sequence of movement is shown;

FIGURE 7 is a sectional view of another embodiment of the subject invention;

FIGURE 8 is a sectional view taken along line 88 of FIGURE 7.

Referring now to FIGURE 1, the subject switch, generally designated by the numeral 10, is illustrated as being mounted with an actuator button 12 protruding through a panel 14 situated near an object 16 Whose movement is to be limited. The clearance between the panel 14 and the object 16 is roughly established when the switch is mounted to the panel 14 and is finally established in a manner to be hereinafter described.

Referring now to FIGURE 4, the actuator button 12 is frictionally disposed in a bore 18 of an actuator 20. The actuator 20 is slidably disposed in an aperture 22 through one wall of the switch body 10. A spring 24 bi- ICC ase-s the actuator 20 away from a flange 26 of the switch body 10. It is understood that the frictional engagement of the actuator button 12 with the bore 18 is greater than the compressive force of the spring 24. The actuator 20 carries a retaining ring 28 that limits the movement of the actuator 20 by coming into contact with an opposite portion of the switch body on which the flange 26 is formed. An extension 30 of the actuator 20 includes a disc-shaped end 32 adapted to engage a contact carrier 34.

Referring now to FIGURE 2, contact carrier 34 is cast from any well-known insulating material and includes a key slot 36 arranged to engage the disc end 32 of the actuator 20. Therefore, the contact carrier 34 is responsive to sliding movement of the actuator 20. A bumper shaped contact element 38 is normally carried in a peripheral groove 40 formed in the contact carrier 34 and is biased away from the main body of the contact carrier 34 by means of a spring 42 engaging the contact element 38 and loosely disposed in an aperture 44 formed in the contact carrier 34.

The switch body 10, as illustrated in FIGURE 2, is substantially hollow and is closed on one end by a cover 46. Cover 46 when positioned against switch body 10 forms a closed compartment within the switch body whose lateral dimension is substantially equal to the size of the contact carrier 34. Key portions 48 formed integrally with the contact carrier 34 cooperate with key slots 50 formed in the cover 46, best seen in FIGURE 5, guide the contact carrier 34 in its operative movement.

Referring now to FIGURE 5, a plurality of contact elements 52a and 52b are illustrated as passing through the cover 46 forming terminal portions on the outside thereof. Contact heads are exposed on the inside of the switch body when the cover 46 is appropriately mounted and are arranged to be contacted by the bumper shaped contact element 38 as the contact carrier is moved up and down, as viewed in FIGURE 5. FIGURE 3 illustrates the contact elements 52a and 52b as operatively positioned with the contact element 38 shown in the two positions it-assumes relative to the contact elements 38 during operation of the subject switch.

Referring to FIGURE 5, a pair of torsion springs 54 are illustrated as having ends 56 and 58. The ends 56 of the springs 54 engage cooperating apertures 60 formed in a wall of the switch body 10. The ends 58 of the springs 54 engage cooperating slots 62 formed in the contact carrier 34. These slots are more clearly seen in FIGURE 2.

Referring to FIGURE 6, the switch is shown in an actuated position with the slot 62 illustrated in progressive stages of movement. When the slot is positioned in the position as illustrated by the dotted line 62a, the switch is at the upper limit of its travel, in which position the bumper shaped contact element 38 engages the pair of fixed contact elements 52a. When the slot 62 is positioned as illustrated. by the dotted line 62b, the switch is centered between complementary pairs of fixed contact elements and the spring 54 is entering its overcentering phase. When the slot 62 is positioned as shown by the solid line 620, the switch has reached a lower limit of travel in which complementary contacts 52b are engaged. It is therefore seen that the springs 54 are contained on one end and pivot in the apertures 60 and are contained on another end by the slots 62. In a preferred mounting, the ends 56 and 58 extend from the periphery of the spring 54 radially. An examination of FIGURE 6 illustrates that the ends 56 and 58 of the springs are positioned closer together when the slot 62 is positioned. at 62b than when positioned at 62a or 620. As the contact carrier 34 moves up and down between two extremes of 3 movement, as illustrated in FIGURE 6, the springs 54 are torsionally compressed and an overcentering action acting on the contact carrier 34 develops as the contact carrier 34 is moved past the point designated by the dotted line 62b.

It is obvious then that, as the contact carrier 34 moves from a position as illustrated in FIGURE 5 to a position as illustrated in FIGURE 6, springs 54 will resist the movement of the contact carrier 34 initially and then, after the slot 62 passes through the point designated by 62b, the springs 54 will assist the contact carrier in its downward movement and the contact carrier 34 will be accelerated. This acceleration will move the bumper shaped contact element 38 very quickly from an engagement with the contacts 52a into engagement with the contacts 521).

It is noted that the key slot 36 formed in the contact carrier 34 is greater in dimension than the thickness of the end 32 of the actuator 20 thereby providing a lost motion connection between the actuator 20 and the contact carrier 34. It is seen that the actuator will be moving at a given rate of speed due to the pressure of an object 16 whose movement is to be limited and, as the object reaches the desired clearance point, the contact carrier 34 very rapidly shifts and breaks an electrical circuit established through the fixed contacts 52a.

When the cycle described is the initial cycling of the switch as mounted, a mechanical force can be exerted on the object 16 after the contact carrier 34 has bottomed out against the switch body to establish the desired clearance between the shifted contact carrier 34 and the movable object 16. Thereafter, subsequent switch actuations will be brought about when the desired limit of movement of the object 16 is reached. The button 12, as previously stated, frictionally engages the bore 18 with greater force than the combined force of the springs 24 and springs 54 so this adjusted position of the button 12 will not be later disturbed.

When it is desired to return the object 16 to a position i of rest away from the panel 14, a movement of the object 16 will allow the spring 24 to become dominant and the spring 24 will pull the contact carrier against the compression of the springs 54 back to the position as illustrated in FIGURE 5. pressive force of the spring 24 is greater than the force required to torsionally compress the springs 54.

The embodiment illustrated in FIGURE 7 differs from the embodiment previously described. only in the substitution of a single spring 64 for the pair of springs 54. Referring to FIGURE 8, the resilient element 64 is seen to be comprised of coils 66 and 68 connected by an omegashaped portion 70. Opposite ends of the coils 66 and It is understood that the com- 68 are arranged to cooperaate with abutments 72 and 74, respectively, formed as a portion of the inside wall of the switch body 10. The omega-shaped loop 70 springs into contact with a groove 76 formed on the lower extremity of the contact carrier 34. The groove and spring relationships are best seen in FIGURE 7.

The operation of the embodiment shown in FIGURE 7 is the same as that described in the previous embodiment in that an overcentering action is generated when the groove 76 passes a plane defined by the abutments 72 and 74. Again, the resilient spring 24 creates more force when compressed during a switch actuation than the compressive force of the spring 64 and a return movement is thereby generated. It is understood that the coils 66 and 68 could be separate springs or formed as two coils on the same spring as illustrated in FIGURE 7. In a given installation, a diflerent rate of travel for the contact carrier could be developed when desired by varying the number of loops of the coils, varying the size of the wire, or by the substitution of separate springs for the single spring illustrated. The exact combination chosen for a given installation would depend on the operating characteristics desired.

The utility of the present invention is particularly apparent in an environment where high amperage loads are carried in the switch and a rapid switching is desired while maintaining a contact cleaning, wiping action of the switch contacts. A typical operative environment for the subject switch could be as a limiter for the travel of an automobile convertible top. In this environment, OX1- dation on switch contacts is likely to occur and is easily dissipated by the wiping action previously described. In addition, high amperage carrying circuits are sometimes utilized for movement of a convertible top and the subject invention is easily adaptable for use in such circuits.

While the embodiments of the present invention, as herein disclosed, constitute preferred forms, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. A limit switch comprising: a switch body having an aperture in one wall thereof; actuator means including a first portion slidably carried in the aperture of said switch body and a second portion disposed within said switch body, said first portion being biased away from said switch body; first means mounted for sliding movement in said switch body between two extremes of movement and having a portion engaging said second portion of said actuator means disposed within said switch body to make said first means responsive to movement of said actuator means, said first means resiliently carrying contact means; fixed contacts carried by one wall of said switch body including terminal portions extending from said switch body and contacting portions carried within said switch body in juxtaposition to the contacts carried by said first means; and second means engaging one wall of said switch body and said first means resisting movement of said first means during a portion of the distance between the two extremes of movement thereof and being adapted to later very quickly shift said first means toward an extreme of movement wherein said resiliently carried contact means engage a different series of fixed contacts as newly positioned than engaging as originally positioned.

2. A limit switch according to claim 1 wherein the first means is a non-conductive block having means for directionally controlling the sliding movement within the switch body and insulatedly carrying the resiliently mounted contact means,

3. A limit switch according to claim 1 wherein the second means is a plurality of coil springs, each having a plurality of terminating outwardly extending ends, one of said ends engaging an inside wall of said switch body and another end operatively engaging said first means.

4. The limit switch according to claim 1 wherein the first means is a single spring element having two coil portions and terminating end portions outwardly projecting from opposed ends of the coils, said ends engaging opposite walls of said switch body and the portion of the element between the coils formed in a manner allowing a resilient engagement of the first means.

5. A limit switch according to claim 4 wherein said single spring element is angularly preformed so that the terminating ends are disposed on a single plane while the spring is in a free position and the portion connecting the plurality of coils is disposed on a different plane than the terminating ends when the spring element is in a free position.

6. A limit switch comprising: a switch body having a substantially hollow interior and an aperture through one wall thereof; an actuator button including a portion arranged to slide in the aperture within the switch body and a portion disposed in the hollow portion of the switch body, said portion slidable in the aperture of the switch body having a telescoping interior portion frictionally engaging a sleeve formed in the button; a contact carrier keyed for directionally controlled movement in the hollow portion of the switch body and having a reilien y carried contact element thereon, said contact carrier including a slot formed in a complementary manner with respect to the portion of the actuator button disposed in the hollow portion of the switch body and operatively engageable therewith; a plurality of fixed contact means carried by one wall of the switch body, said fixed contact means showing a first portion extending from the switch body and forming terminals and a second portion of said fixed contact means carried within the hollow portion of the switch body in juxtaposition to the resiliently carried contact element of the contact carrier; and resilient means engaging an inside wall of the hollow switch body and having a portion engaging said contact carrier biasing said contact carrier and said actuator button in a manner allowing a maximum extension of the actuator button from the switch body, said resilient means being drivable over center from a poised position in response to a sliding movement of the contact carrier induced by the actuator button to move said resiliently mounted contact element very rapidly between several References Cited by the Examiner UNITED STATES PATENTS 1,103,020 7/1914 Austin.

2,548,678 4/ 1951 Ohenour 200-76 2,627,006 1/ 1953 Lawson et a1 200164 X 2,919,319 12/1959 Chapin et al. 20067 3,037,099 5/ 1962 Aandewiel ZOO-67 BERNARD A. GILHEANY, Primary Examiner.

T. D. MACBLAIN, Assistant Examiner. 

1. A LIMIT SWITCH COMPRISING: A SWITCH BODY HAVING AN APERTURE IN ONE WALL THEREOF; ACTUATOR MEANS INCLUDING A FIRST PORTION SLIDABLY CARRIED IN THE APERTURE OF SAID SWITCH BODY AND A SECOND PORTION DISPOSED WITHIN SAID SWITCH BODY, SAID FIRST PORTION BEING BIASED AWAY FROM SAID SWITCH BODY; FIRST MEANS MOUNTED FOR SLIDING MOVEMENT IN SAID SWITCH BODY BETWEEN TWO EXTREMES OF MOVEMENT AND HAVING A PORTION ENGAGING SAID SECOND PORTION OF SAID ACTUATOR MEANS DISPOSED WITHIN SAID SWITCH BODY TO MAKE SAID FIRST MEANS RESPONSIVE TO MOVEMENT OF SAID ACTUATOR MEANS, SAID FIRST MEANS RESILIENTLY CARRYING CONTACT MEANS; FIXED CONTACTS CARRIED BY ONE WALL OF SAID SWITCH BOODY AND CONTACTING PORTIONS EXTENDING FROM SAID SWITCH BODY AND CONTACTING PORTIONS CARRIED WITHIN SAID SWITCH BODY IN JUXTAPOSITION TO THE CONTACTS CARRIED BY SAID FIRST BODY IN CONTACTING PORTIONS CARRIED ONE WALL OF SAID SWITCH BODY AND SAID FIRST MEANS RESISTING MOVEMENT OF SAID FIRST MEANS DURING A PORTION OF THE DISTANCE BETWEEN THE TWO EXTREMES OF MOVEMENT THEREOF AND BEING ADAPTED TO LATER VERY QUICKLY SHIFT SAID FIRST MEANS TOWARD AN EXTREME OF MOVEMENT WHEREIN SAID RESILIENT CARRIED CONTACT MEANS ENGAGE A DIFFERENT SERIES OF FIXED CONTACTS AS NEWLY POSITIONED THAN ENGAGING AS ORIGINALLY POSITIONED. 